#include<iostream>
#include<cmath>
#include<iomanip>
#include<cstdio>
using namespace std;
double distant(double x1, double y1, double x2, double y2)
{
	return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
int main()
{
	double x1, y1, x2, y2, x3, y3;
	cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
	double ret1 = distant(x1, y1, x2, y2);
	double ret2 = distant(x1, y1, x3, y3);
	double ret3 = distant(x2, y2, x3, y3);
	double girth = ret1 + ret2 + ret3;
	cout << fixed << setprecision(2) << girth << endl;
	return 0;
}